I experience this issue repeatedly.
I have 2 PDF files, and double click the 1st file to open. It launches Acrobat, and the file opens.
I want to open a second PDF file, to view and compare. I double click the second file, and nothing happens. Sometimes after 10-20 seconds the 2nd file opens, but many times, nothing happens.
Launching the Task Manager shows me multiple instances of Acrobat running, and many Adobe "Background processes" (Adobe AcroCEF (32 bit, Adobe CEP HTML Engine)
The only fix I have found is to "End task" on the many "Adobe CEP HTML Engine" instances. Eventually it releases the application to run, and I am able to open multiple PDF documents by double clicking them, one at a time.
Acrobat Pro - Version 2023.006.20320
Windows 10 Pro - Version 22H2, OS build 19045.3208